So I made some upgrades to my old CR-10S, including a Micro Swiss direct drive extruder, and since then I don't seem to have control of my extrusion rate.

Micro Swiss recommended a starting value of 130 for the e-step setting, and I did a calibration and decided that 137 worked perfectly on my setup. That seemed reasonably close to their recommended value.

But I started having non-stop bed adhesion problems, print after print. I'm sure my nozzle height is correct, and the purge line always lays down very nicely. But for some reason, the first layer of my print always winds up very under-extruded. I'm almost certain this is what's causing my adhesion problems.

Before the upgrade, I always printed PLA at 95% flow rate, except for the first layer, which I bumped up to 120%. That always gave me a very nice squish on the first layer, and produced a beautiful mirror finish on my glass bed, fully covered with no sign of individual beads. I've succeeded in printing up a few test items, and I'm finding that 85% flow rate is now giving my prints a nice body and top, but I've tried as much as 600% flow rate on the first layer, and though it's much better covered, the beads are still distinct and not fully merged together. And I can't help thinking something is very wrong if I need 600% flow rate to even approach a smooth first layer.

I'm not sure what to think at this point. I've tried bumping up the e-step setting even further, with similar results -- I need a ridiculously high setting to achieve anything like a clean first layer, and then I need a very low setting (like 15%) for the overall flow rate to make the body and top layers look good.

Any thoughts? At this point I'm not sure what to think. I've checked and re-checked all the hardware, and nothing seems to be wrong with any of it. The nozzle to bed distance is exactly what it should be (I use feeler gauges to verify), the extruder isn't missing any steps or skipping, the e-step calibration hasn't changed, the frame of the printer is square and tight, belts are properly adjusted, carriage eccentrics are properly tightened. I don't have an ABL, but I did the manual mesh and the bed seems very flat and consistent as measured by feeler gauge.